We shall strive more particularly here below in this document to describe the issues and problems existing in the field of medical imaging and more particularly in the field of ocular imaging (viewing of the internal structures of the eye) which the inventors of the present patent application have faced. The invention is of course not limited to this particular field of application but is of interest for any endoscopy device (or endoscope) that has to cope with similar or proximate issues and problems.
The endoscopic devices used at present to examine the structure of the human eye comprise a rigid invasive part, called an optical guide head, intended to penetrate a patient's organ. This optical guide head is formed generally by a metal tube with an external diameter of some millimeters (for example a stainless-steel tube with an external diameter of 0.9 mm) containing an optical system formed either by a series of optical lenses or by a bundle of optical fibers agglutinated with a cohesion bonder.
Typically, the bundle of optical fibers is connected to an image sensor (such as a video camera) by means of an adapter, the image sensor itself being connected to a display screen. The bundle of optical fibers enables the images of the observed object to be conveyed to the image sensor, after these images are shaped, retransmits them in real time to the display screen.
The metal tube is also provided with a system of illumination by optical fibers used to convey the light from an external pack, provided with a light source, up to the observation zone.
A gripping means is fixedly joined to the metal tube to facilitate the handling of the endoscope and spatial position-finding.
This type of endoscope nevertheless has numerous drawbacks.
To ensure the rigidity of the optical guide head when it is inserted into the patient's organ, the metal tube must have a certain thickness. This limits the quantity of light reaching the image sensor. Since the amount of detail captured by the image sensor is thus limited, the quality of the images rendered on the screen is relatively lowered.
In addition, the optical guide heads, whether they are formed by optical lenses or optical fibers, are technically complex and costly to manufacture.
Indeed, a guide head using optical lenses requires a very precise assembly of a plurality of optical lenses in a metal tube having limited dimensions owing to the requirements of miniaturization (the internal diameter of the tube could sometimes be as little as a few hundreds of micrometers), to form the optical objective of the endoscope. The lenses are particularly fragile optical components.
In addition, the cable of the guide head generally comprises a bundle of optical fibers of great length (capable of reaching up to several meters) giving rise to non-negligible losses of light. The optical fiber cable is substantially sized and does not enable easy handling of the endoscope.
Finally, to avoid any risk of infection of the patient, it is necessary to have aseptic endoscopic equipment available. To this end, the endoscopes are sterilized before each use (for example by autoclave sterilization), often leading to premature ageing of the endoscopes. This includes not only the optical guide head in direct contact with the patient and the gripping means but also the optical fiber cables. These features make the autoclave operations difficult and a source of breakage and deterioration of the system.
There is therefore a need for a low-cost endoscopic device that is simple to use offering guarantees in terms of health safety and enabling the rendering of high-quality images.